<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>font-weight</title>
    <style>
        .div1{
            font-weight: normal; /*400*/
            font-weight: bold;   /*700*/
            font-weight: bolder;
            font-weight: lighter;
            font-weight: 100;
        }
    </style>
</head>
<body>
    <div class="div1">学如逆水行舟，不进则退！</div>
</body>
</html>
